The Great Megapixel Debate

Your personal digital camera gives you a six megapixel image. Your teenage daughter’s cell phone captures two megapixel photos. Why are you satisfied that the camera in your surveillance system is limited to 0.3 megapixels (at 4CIF)? Chances are...


Your personal digital camera gives you a six megapixel image. Your teenage daughter’s cell phone captures two megapixel photos. Why are you satisfied that the camera in your surveillance system is limited to 0.3 megapixels (at 4CIF)? Chances are that your DVR is programmed to capture only a quarter (CIF) of the camera’s maximum resolution (4CIF) to provide a paltry .075 megapixels?
It doesn’t have to be that way. With megapixel camera sales doubling year after year, more manufacturers are providing a broad set of products for both indoor and outdoor applications. As IP cameras are becoming more commonplace for security applications, end-users are taking advantage of the megapixel resolutions to improve image quality, reduce the number of cameras and to provide better overall situational awareness.

Manufacturers
IQinvision, San Juan Capistrano, Calif., and Arecont Vision, Glendale, Calif., have established themselves as leaders in megapixel camera products for security. Until recently, megapixel cameras were considered a niche product in the growing IP camera market. As IP camera solutions have become more commonplace, upstarts like Avigilon, Vancouver, B.C., have entered the market as well as established camera providers such as Axis, Bosch and Sony. The cost of a 1.3 megapixel camera starts as low as $500 suggested retail. Several manufacturers state a strategy to aggressively price their cameras to compare favorably with name brand analog cameras.
Most megapixel products use Motion JPEG (MJPEG) compression. Like standard resolution IP cameras, MPEG-4 and H.264 products are beginning to surface on the market.

Management software
Like any network camera, megapixel units are typically managed with video management software (VMS). Most camera manufacturers provide a basic video management and recording solution. Many manufacturers also partner with open software solutions such as Genetec and Milestone.

To date, many VMS systems have typically treated megapixel cameras like most standard resolutions network cameras and have not integrated key features that are unique to megapixel cameras:
Image cropping modifies the aspect ratio from the traditional 4:3 to 16:9. This offers better viewing for security video which often has more interest in the horizontal direction. Image cropping optimizes each scene by clipping the image to eliminate unwanted, wasted video to save bandwidth and storage.

Digital pan-tilt-zoom (PTZ) control allows the user to virtually move around and zoom into an image using a smaller viewing window. The system still records the entire image since movement is virtual.

Analog standards are limited
The analog video standards (NTSC) that have defined North American CCTV since the 1950s limit video resolution to 640 x 480 pixels (4CIF). This equates to an overall image resolution of about 0.3 megapixels. Digital cameras are not bound by the NTSC resolution standards. While the majority of the network cameras sold each year are limited to standard resolutions, camera sales of 1.3, 2 and 5 megapixel are growing by at least 100 percent each year.
The major criticism of megapixel cameras is the large data rate that can be generated to consume precious network bandwidth and disk storage. The increased resolution puts additional performance demands on both the camera and the overall surveillance system.

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